I'm sorry I can't say whether your father's feeling of sick stomach, tiring, etc are normal systems of AD. AD from what I understand from the doctor, as well as from support groups, is like taking a large book. When you open it, the first pages, are the recent days of their life. Once you flip the pages, these memories they have from day to day are gone forever. This is why they remember long term memory, things from the far distant past, as when they just started out in life. As they reach the end of the book, they will actually only remember things from the far past of their own lives. One thing to remember is that with AD from what I have learned thru 2 family members that had it and are gone now, (mother has it now) everyone is different. My one aunt was hateful, and full of anger and wanted to wander off from the nursing home she was in, my other aunt was quiet, and calm thru her ordeal. The disease not only takes away their memories, it creates complications to their physical bodies. A person doesn't die from AD, but from the complications it creates, because the brain slowly dies, and after this part or that part is gone, then parts of the body start to shut down. My aunt was bedridden for 2 years, and could not do anything by herself, occasionally maybe about once a month, she would say THANK YOU. Because at this stage, she was unable to speak, sit, eat, literally anything and everything was done for then. As far as the length of time, a person suffers with this --it can vary. This is the main reason the disease, I believe, is called THE LONG GOODBYE. I have heard of people having it from 10 to 20 years, before they pass on. It's not easy for the caretakers, and it is also rough of the patient, because while they still have some sense to theirselves, they just can't understand why this is happening to them. It's sad, real sad, just make your father happy, content, and LOVE him. I pray for all AD patients, and their caregivers daily, because I know being one myself, it's not an easy life for either one.